U.S. patent application number 17/545353 was filed with the patent office on 2022-09-08 for planar heater, fixing device, image forming apparatus, and method of manufacturing planar heater.
This patent application is currently assigned to Ricoh Company, Ltd.. The applicant listed for this patent is Tomoya ADACHI, Yuusuke FURUICHI, Yukimichi SOMEYA. Invention is credited to Tomoya ADACHI, Yuusuke FURUICHI, Yukimichi SOMEYA.
Application Number | 20220283530 17/545353 |
Document ID | / |
Family ID | 1000006051855 |
Filed Date | 2022-09-08 |
United States Patent
Application |
20220283530 |
Kind Code |
A1 |
ADACHI; Tomoya ; et
al. |
September 8, 2022 |
PLANAR HEATER, FIXING DEVICE, IMAGE FORMING APPARATUS, AND METHOD
OF MANUFACTURING PLANAR HEATER
Abstract
A planar heater includes a base, a resister pattern, a conductor
pattern, a power supply electrode, and a base pattern. The base
includes a surface portion made of an insulative material. The
resistor pattern is on the base. The conductor pattern is on the
base and electrically coupled to the resistor pattern. The power
supply electrode is electrically coupled to the conductor pattern.
The base pattern is on the base and made of a material different
from a material of the surface portion of the base to print visible
identification information.
Inventors: |
ADACHI; Tomoya; (Kanagawa,
JP) ; FURUICHI; Yuusuke; (Kanagawa, JP) ;
SOMEYA; Yukimichi; (Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ADACHI; Tomoya
FURUICHI; Yuusuke
SOMEYA; Yukimichi |
Kanagawa
Kanagawa
Saitama |
|
JP
JP
JP |
|
|
Assignee: |
Ricoh Company, Ltd.
Tokyo
JP
|
Family ID: |
1000006051855 |
Appl. No.: |
17/545353 |
Filed: |
December 8, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B 2203/017 20130101;
G03G 15/2053 20130101; H05B 2203/016 20130101; H05B 3/26 20130101;
G03G 15/80 20130101 |
International
Class: |
G03G 15/20 20060101
G03G015/20; H05B 3/26 20060101 H05B003/26; G03G 15/00 20060101
G03G015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 2, 2021 |
JP |
2021-032600 |
Claims
1. A planar heater comprising: a base including a surface portion
made of an insulative material; a resistor pattern on the base; a
conductor pattern being on the base and electrically coupled to the
resistor pattern; a power supply electrode electrically coupled to
the conductor pattern; and a base pattern being on the base and
made of a material different from a material of the surface portion
of the base to print visible identification information.
2. The planar heater according to claim 1, wherein the base pattern
is screen-printed on the base, and wherein the identification
information is printed on the base pattern with ink having a color
different from a color of the base pattern.
3. The planar heater according to claim 1, wherein the power supply
electrode and the base pattern are made of a same silver-based
material and not electrically connected each other.
4. The planar heater according to claim 1, wherein the power supply
electrode and the base pattern are on one end portion of the base
in a width direction of the base.
5. The planar heater according to claim 1, further comprising a
cover covering the base pattern on which the identification
information is printed.
6. The planar heater according to claim 1, wherein the base is made
of the insulative material.
7. The planar heater according to claim 1, wherein the base
includes: a main base made of a conductive material; and an
insulation layer on the main base.
8. A fixing device comprising: the planar heater according to claim
1; a fixing belt configured to be heated by the planar heater; and
a pressure rotator configured to press the planar heater via the
fixing belt.
9. The fixing device according to claim 8, further comprising: a
holder holding the planar heater; a pair of flanges supporting both
ends of the fixing belt in a width direction of the fixing belt;
and a housing holding the pair of flanges and both ends of the
holder in a width direction of the holder, wherein the base pattern
of the planar heater is at a position outside the housing in a
width direction of the housing.
10. The fixing device according to claim 9, wherein the position
outside the housing in the width direction is visible from outside
the fixing device.
11. An image forming apparatus comprising the fixing device
according to claim 8.
12. A method of manufacturing a planar heater, comprising: forming
a resistor pattern and a conductor pattern electrically connected
to the resistor pattern on a base including a surface portion made
of an insulative material; and forming, on the base, a power supply
electrode electrically coupled to the conductor pattern and a base
pattern made of a material different from a material of the surface
portion of the base to print visible identification information.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application is based on and claims priority
pursuant to 35 U.S.C. .sctn. 119(a) to Japanese Patent Application
No. 2021-032600, filed on Mar. 2, 2021 in the Japan Patent Office,
the entire disclosure of which is incorporated by reference
herein.
BACKGROUND
Technical Field
[0002] This disclosure relates to a planar heater including a
resister pattern, a fixing device incorporating the planar heater,
an image forming apparatus such as a copier, printer, facsimile
machine, a multi-functional apparatus including at least two
functions of the copier, printer, and facsimile machine, and a
method of manufacturing a planar heater.
Related Art
[0003] One type of fixing device in an image forming apparatus such
as a copier or a printer uses a planar heater (a resistive heat
generator) as a heating device to heat a fixing belt.
[0004] Specifically, the fixing device includes a fixing belt
(fixing sleeve), a pressure roller as a pressure rotator, and a
planar heater (a resistive heat generator) that is pressed against
the pressure roller via the fixing belt. As a driver drives and
rotates the pressure roller, the fixing belt rotates in accordance
with rotation of the pressure roller by friction therebetween
generated at the fixing nip. As a sheet bearing a toner image is
conveyed through the fixing nip, the fixing belt heated by the
heater and the pressure roller fix the toner image on the sheet
under heat and pressure. These parts are marked with a lot number
or the like.
SUMMARY
[0005] This specification describes an improved planar heater that
includes a base, a resister pattern, a conductor pattern, a power
supply electrode, and a base pattern. The base includes a surface
portion made of insulative material. The resistor pattern is on the
base. The conductor pattern is on the base and electrically coupled
to the resistor pattern. The power supply electrode is electrically
coupled to the conductor pattern. The base pattern is on the base
and made of a material different from a material of the surface
portion of the base to print visible identification
information.
[0006] This specification further describes an improved method of
manufacturing a planar heater including following processes. One
process is forming a resistor pattern and a conductor pattern
electrically connected to the resistor pattern on a base including
a surface portion made of an insulative material. The other process
is forming, on the base, a power supply electrode electrically
coupled to the conductor pattern and a base pattern made of a
material different from a material of the surface portion of the
base to print visible identification information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] A more complete appreciation of the disclosure and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0008] FIG. 1 is a schematic view of a configuration of an image
forming apparatus according to an embodiment of the present
disclosure;
[0009] FIG. 2 is a schematic view of a configuration of a fixing
device in the image forming apparatus of FIG. 1;
[0010] FIG. 3 is a top view of the fixing device illustrating a
part extending in a width direction that is a lateral direction in
FIG. 3;
[0011] FIG. 4 is a schematic cross-sectional view of a fixing belt
extending in the width direction and guides included in the fixing
device of FIG. 3;
[0012] FIG. 5 is a schematic top view and a schematic side view of
a planar heater according to an embodiment of the present
disclosure;
[0013] FIGS. 6A and 6B are schematic top views and schematic side
views to illustrate a manufacturing processes of the planar heater
according to the embodiment;
[0014] FIG. 7 is a schematic top view and a schematic side view of
the planar heater of FIG. 5 coupled to the fixing device; and
[0015] FIGS. 8A and 8B are schematic top views and schematic side
views to illustrate a manufacturing process of the planar heater
according to a variation.
[0016] The accompanying drawings are intended to depict embodiments
of the present disclosure and should not be interpreted to limit
the scope thereof. The accompanying drawings are not to be
considered as drawn to scale unless explicitly noted. Also,
identical or similar reference numerals designate identical or
similar components throughout the several views.
DETAILED DESCRIPTION
[0017] In describing embodiments illustrated in the drawings,
specific terminology is employed for the sake of clarity. However,
the disclosure of this patent specification is not intended to be
limited to the specific terminology so selected and it is to be
understood that each specific element includes all technical
equivalents that operate in a similar manner and achieve similar
results.
[0018] Referring now to the drawings, embodiments of the present
disclosure are described below. As used herein, the singular forms
"a," "an," and "the" are intended to include the plural forms as
well, unless the context clearly indicates otherwise.
[0019] Embodiments of the present disclosure are described below
with reference to drawings. Identical reference numerals are
assigned to identical components or equivalents and a description
of those components is simplified or omitted.
[0020] Initially, with reference to FIG. 1, a configuration and
operation of an image forming apparatus 1 according to a present
embodiment of the present disclosure is described below.
[0021] As illustrated in FIG. 1, the image forming apparatus 1
according to the present embodiment is a tandem-type color printer.
The image forming apparatus 1 includes a bottle housing 101 in an
upper portion of the image forming apparatus 1. The bottle housing
101 accommodates four toner bottles 102Y, 102M, 102C, and 102K
containing fresh yellow, magenta, cyan, and black toners,
respectively, and being detachably attached to the bottle housing
101 for replacement.
[0022] Under the bottle housing 101, an intermediate transfer unit
85 is disposed. Facing an intermediate transfer belt 78 of the
intermediate transfer unit 85, image forming devices 4Y 4M, 4C, and
4K are arranged side by side to form toner images of yellow,
magenta, cyan, and black, respectively.
[0023] The image forming devices 4Y, 4M, 4C, and 4K include
photoconductor drums 5Y, 5M, 5C, and 5K, respectively. Each of the
photoconductor drums 5Y, 5M, 5C, and 5K is surrounded by a charger
75, a developing device 76, a cleaner 77, a discharger, and the
like. Image forming processes including a charging process, an
exposure process, a developing process, a primary transfer process,
and a cleaning process are performed on an outer circumferential
surface of each of the photoconductor drums 5Y, 5M, 5C, and 5K,
forming yellow, magenta, cyan, and black toner images on the
photoconductor drums 5Y, 5M, 5C, and 5K, respectively.
[0024] A motor drives and rotates the photoconductor drums 5Y, 5M,
5C, and 5K clockwise in FIG. 1. The charger 75 disposed opposite
each of the photoconductor drums 5Y, 5M, 5C, and 5K uniformly
charges the outer circumferential surface thereof in the charging
process.
[0025] After the charging process, the charged outer
circumferential surface of each of the photoconductor drums 5Y, 5M,
5C, and 5K reaches an irradiation position at which an exposure
device 3 irradiates and scans the photoconductor drums 5Y, 5M, 5C,
and 5K with laser beams L, irradiating and scanning the
photoconductor drums 5Y, 5M, 5C, and 5K with the laser beams L
forms electrostatic latent images according to yellow, magenta,
cyan, and black image data in the exposure process.
[0026] After the exposure process, the irradiated and scanned outer
circumferential surface of each of the photoconductor drums 5Y, 5M,
5C, and 5K reaches a developing position at which the developing
device 76 is disposed opposite each of the photoconductor drums 5Y,
5M, 5C, and 5K, and the developing device 76 develops the
electrostatic latent image formed on the respective photoconductor
drums 5Y, 5M, 5C, and 5K, thus forming yellow, magenta, cyan, and
black toner images on the photoconductor drums 5Y, 5M, 5C, and 5K
in the developing process.
[0027] After the developing process, the yellow, magenta, cyan, and
black toner images formed on the photoconductor drums 5Y, 5M, 5C,
and 5K reach primary transfer nips formed between the
photoconductor drums 5Y, 5M, 5C, and 5K and the intermediate
transfer belt 78 by four primary transfer bias rollers 79Y, 79M,
79C, and 79K pressed against the four photoconductor drums 5Y, 5M,
5C, and 5K via the intermediate transfer belt 78, respectively, and
the yellow, magenta, cyan, and black toner images are primarily
transferred onto the intermediate transfer belt 78 in a primary
transfer process. After the primary transfer process, residual
toner failed to be transferred onto the intermediate transfer belt
78 remains on the photoconductor drums 5Y, 5M, 5C, and 5K
slightly.
[0028] After the primary transfer process, the residual toner on
each of the photoconductor drums 5Y, 5M, 5C, and 5K reaches a
cleaning position at which the cleaner 77 is disposed opposite each
of the photoconductor drums 5Y, 5M, 5C, and 5K, and a cleaning
blade of the cleaner 77 mechanically collects the residual toner
from each of the photoconductor drums 5Y, 5M, 5C, and 5K in the
cleaning process.
[0029] Finally; the cleaned outer circumferential surface of each
of the photoconductor drums 5Y, 5M, 5C, and 5K reaches a
discharging position at which the discharger is disposed opposite
each of the photoconductor drums 5Y, 5M, 5C, and 5K, and the
discharger eliminates residual potential from each of the
photoconductor drums 5Y, 5M, 5C, and 5K.
[0030] Thus, a series of image forming processes performed on the
photoconductor drums 5Y, 5M, 5C, and 5K is finished.
[0031] The yellow, magenta, cyan, and black toner images formed on
the photoconductor drums 5Y, 5M, 5C, and 5K in the developing
process are primarily transferred onto an outer circumferential
surface of the intermediate transfer belt 78 such that the yellow,
magenta, cyan, and black toner images are superimposed on a same
position on the intermediate transfer belt 78. Thus, a color toner
image is formed on the intermediate transfer belt 78.
[0032] The intermediate transfer unit 85 includes the intermediate
transfer belt 78, the four primary transfer bias rollers 79Y, 79M,
79C, and 79K, a secondary transfer backup roller 82, a cleaning
backup roller 83, a tension roller 84, and an intermediate transfer
belt cleaner 80. The intermediate transfer belt 78 is stretched
taut across and supported by the three rollers, that is, the
secondary transfer backup roller 82, the cleaning backup roller 83,
and the tension roller 84. One of the three rollers, that is, the
secondary transfer backup roller 82 drives and rotates the
intermediate transfer belt 78 in a rotation direction indicated by
arrow in FIG. 1.
[0033] The four primary transfer bias rollers 79Y, 79M, 79C, and
79K sandwich the intermediate transfer belt 78 together with the
four photoconductor drums 5Y, 5M, 5C, and 5K, respectively, thus
forming the four primary transfer nips between the intermediate
transfer belt 78 and the photoconductor drums 5Y, 5M, 5C, and 5K.
Each of the primary transfer bias rollers 79Y, 79M, 79C, and 79K is
applied with a primary transfer bias having a polarity opposite a
polarity of electric charge of toner.
[0034] The intermediate transfer belt 78 is moved in the direction
indicated by arrow in FIG. 1 and sequentially passes through the
primary transfer nips formed by the primary transfer bias rollers
79Y, 79M, 79C, and 79K. The yellow, magenta, cyan, and black toner
images on the photoconductor drums 5Y, 5M, 5C, and 5K are primarily
transferred to and superimposed on the intermediate transfer belt
78, thereby forming the color toner image.
[0035] Subsequently, the intermediate transfer belt 78 carrying the
color toner image reaches a position opposite the secondary
transfer roller 89. At the position, the secondary transfer backup
roller 82 and the secondary transfer roller 89 press against each
other via the intermediate transfer belt 78, and the contact
portion therebetween is hereinafter referred to as a secondary
transfer nip. The four-color toner image formed on the intermediate
transfer belt 78 is transferred onto the sheet P conveyed to the
position of the secondary transfer nip. At this time, untransferred
toner that is not transferred onto the sheet P remains on the
surface of the intermediate transfer belt 78. The intermediate
transfer belt 78 reaches a position opposite the intermediate
transfer belt cleaner 80. At the position, the intermediate
transfer belt cleaner 80 collects the untransferred toner from the
intermediate transfer belt 78.
[0036] Thus, a sequence of image forming processes performed on the
intermediate transfer belt 78 is completed.
[0037] The sheet P conveyed through the secondary transfer nip is
conveyed from a sheet feeder 12 disposed in a lower portion of the
body of the image forming apparatus 1 through a feed roller 97, a
registration roller pair 98 (e.g., a timing roller pair), and the
like. Specifically, the sheet feeder 12 contains a stack of
multiple sheets P such as sheets of paper stacked on one on
another. As the feed roller 97 rotates counterclockwise in FIG. 1,
the feed roller 97 feeds an uppermost sheet P in the sheet feeder
12 to a roller nip between the registration roller pair 98.
[0038] The registration roller pair 98 stops rotating temporarily,
stopping the sheet P with a leading edge of the sheet P nipped in
the roller nip between the registration roller pair 98.
Subsequently; the registration roller pair 98 rotates to convey the
sheet P to the secondary transfer nip, timed to coincide with the
arrival of the color toner image on the intermediate transfer belt
78, and the secondary transfer roller 89 transfers the desired
color toner image onto the sheet P.
[0039] After the secondary transfer roller 89 transfers the color
image onto the sheet P at the secondary transfer nip, the sheet P
is conveyed to a fixing device 20. In the fixing device 20, a
fixing belt 21 and a pressure roller 31 apply heat and pressure to
the sheet P to fix the transferred color toner image on the sheet
P, which is referred to as a fixing process.
[0040] After the fixing process, the sheet P bearing the fixed
toner image is conveyed through a roller nip formed by an output
roller pair 99 and ejected by the output roller pair 99 onto an
outside of the image forming apparatus 1. The sheets P ejected by
the output roller pair 99 are sequentially stacked as output images
on a stack section 100.
[0041] Thus, a series of image forming processes performed by the
image forming apparatus 1 is completed.
[0042] Referring to FIGS. 2 to 4, the following describes a
configuration and operation of the fixing device 20 incorporated in
the image forming apparatus 1 described above.
[0043] The fixing device 20 conveys the sheet P (bearing an unfixed
toner image) while heating the sheet P. With reference to FIGS. 2
to 4, the fixing device 20 includes a fixing belt 21 serving as a
fixing rotator, a reinforcement 30, a planar heater 24, a pressure
roller 31 serving as a pressure rotator, and a temperature sensor
40 as a temperature detector. The fixing device 20 can be attached
to and detached from the body of the image forming apparatus 1 by
rotating an opening and closing cover 110 (see FIG. 1) on a hinge
110a in the body of the image forming apparatus 1.
[0044] The fixing belt 21 is an endless belt disposed in contact
with an outer circumferential surface of the pressure roller 31 and
driven to rotate by rotation of the pressure roller 31. The fixing
belt 21 is a thin, flexible endless belt driven to rotate
counterclockwise in FIG. 2, that is, in a rotation direction
indicated by arrow in FIG. 2. The fixing belt 21 is constructed of
a base layer serving as an inner circumferential surface (i.e., a
sliding contact surface of the fixing belt 21 sliding over the
planar heater 24), an elastic layer coating the base layer, and a
release layer coating the elastic layer, which define a total
thickness of the fixing belt 21 not greater than 1 mm.
[0045] The base layer of the fixing belt 21 has a thickness in a
range of from 30 .mu.m to 50 .mu.m and is made of metal, such as
nickel or stainless steel, or resin such as polyimide.
[0046] The elastic layer of the fixing belt 21 has a thickness of
100 .mu.m to 300 .mu.m and is made of rubber such as silicone
rubber, foamable silicone rubber, or fluoro rubber. The elastic
layer absorbs slight surface asperities of the fixing belt 21 at a
fixing nip formed between the fixing belt 21 and the pressure
roller 31, facilitating even heat conduction from the fixing belt
21 to the color toner image T on the sheet P and thereby
suppressing formation of an orange peel image on the sheet P.
[0047] The release layer of the fixing belt 21 has a thickness in a
range of from 5 .mu.m to 50 .mu.m and is made of material such as
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA),
polytetrafluoroethylene (PTFE), polyimide, polyether imide, and
polyether sulfone (PES). The release layer facilitates separation
or peeling-off of toner of the color toner image T on the sheet P
from the fixing belt 21.
[0048] Inside a loop of the fixing belt 21, the planar heater 24, a
holder 23 and the reinforcement 30 are disposed
[0049] The planar heater 24 is disposed opposite the inner
circumferential surface of the fixing belt 21. The planar heater 24
presses against the pressure roller 31 via the fixing belt 21 to
form the fixing nip through which the sheet P is conveyed. The
planar heater 24 is disposed inside the loop formed by the fixing
belt 21 such that the inner circumferential surface of the fixing
belt 21 slides over the planar heater 24. The planar heater 24
presses against the pressure roller 31 via the fixing belt 21 to
form the fixing nip between the fixing belt 21 and the pressure
roller 31, through which the sheet P is conveyed. As described
above, the planar heater 24 functions as a nip formation pad that
is a member forming the fixing nip. The planar heater 24 may
include a surface layer or a sheet made of low friction material
such as PTFE on the surface of the planar heater 24 to reduce
sliding friction between the fixing belt 21 and the planar heater
24.
[0050] In addition, the planar heater 24 includes a resistor
pattern 26 (see FIGS. 5 to 8B) formed on a portion that is in
sliding contact with the inner circumferential surface of the
fixing belt 21. A power supply supplies electric power to the
resistor pattern 26 serving as a resistive heat generator, and the
resistor pattern 26 generates heat according to the resistance of
the resistor pattern 26 to heat the fixing belt 21. As described
above, the planar heater 24 also functions as a heating unit
(heating body) that heats the fixing belt 21.
[0051] In the present embodiment, the holder 23 holds the planar
heater 24. As illustrated in FIG. 3, a housing 43 of the fixing
device 20 holds both end portions of the holder 23 in a width
direction of the holder 23 that is the direction perpendicular to a
plane on which FIG. 2 is illustrated and the lateral direction in
FIG. 3.
[0052] The planar heater 24 is described below in detail with
reference to FIGS. 5 to 7, etc.
[0053] As described above, the planar heater 24 (the resistor
pattern 26) disposed inside the loop of the fixing belt 21 directly
heats the fixing belt 21. Heat is conducted from an outer
circumferential surface of the fixing belt 21 heated by the planar
heater 24 to the toner image T on the sheet P.
[0054] Output of the planar heater 24 is controlled based on the
temperature of the outer circumferential surface of the fixing belt
21 detected by the temperature sensor 40. The temperature sensor 40
is a thermopile, a thermistor, or the like, disposed opposite the
outer circumferential surface of the fixing belt 21. The Planar
heater 24 controlled as described above heats the fixing belt 21 to
a desired fixing temperature.
[0055] Referring to FIG. 4, a pair of flanges 42 as guides guide
ends of the inner circumferential surface of the fixing belt 21 in
a width direction of the fixing belt 21 such that the fixing belt
21 maintains a substantially cylindrical posture.
[0056] Specifically; the two flanges 42 are made of a
heat-resistant resin material or the like and are fitted into both
sides in the width direction of the housing 43 of the fixing device
20. Each of the flanges 42 includes a guide 42a and a stopper. The
guide 42a supports the fixing belt 21 to maintain a substantially
cylindrical posture thereof. The stopper restricts motion or skew
of the fixing belt 21 in the width direction thereof.
[0057] In addition, as illustrated in FIG. 3, the fixing device 20
according to the present embodiment includes compression springs 52
as biasing members. Biasing force of the compression springs 52
press the flanges 42. As a result, the fixing belt 21, the planar
heater 24, and the holder 23 are pressed against the pressure
roller 31 by the biasing force.
[0058] The flanges 42 support both end portions of the fixing belt
21 in the width direction of the fixing belt 21 except for both end
portions corresponding to the fixing nip so that the planar heater
24 can form the fixing nip.
[0059] As described above, the inner circumferential surface of the
fixing belt 21 is loosely contacted only by the planar heater 24
and the flanges 42 at respective ends of the fixing belt 21 in the
width direction thereof. No other component, such as a belt guide,
contacts the inner circumferential surface of the fixing belt 21 to
guide the fixing belt 21 as it rotates.
[0060] The fixing device 20 according to the present embodiment
includes the reinforcement 30 that is disposed inside the loop of
the fixing belt 21 so as to be in contact with the pressure roller
31 via the holder 23, the planar heater 24, and the fixing belt 21.
The reinforcement 30 reinforces the holder 23 and the planar heater
24 forming the fixing nip, enhancing the mechanical strength of the
holder 23 and the planar heater 24. The reinforcement 30 is
installed in the housing 43 by screw fastening or the like.
[0061] The reinforcement 30 receiving the pressure from the
pressure roller 31 via the holder 23, the planar heater 24, and the
fixing belt 21 prevents a disadvantage that the pressure from the
pressure roller 31 largely deforms the planar heater 24 (and the
holder 23) at the fixing nip. Preferably, the reinforcement 30 is
made of metal having an increased mechanical strength, such as
stainless steel or iron, to ensure the above-described function.
The holder 23 may be made of a resin material or a metallic
material. Preferably, the holder 23 is made of a resin material
that has a rigidity great enough to prevent substantial bending
even if the holder 23 receives the pressure from the pressure
roller 31 and has heat resistance and thermal insulation, such as
liquid crystal polymer (LCP), polyamide imide (PAI), polyether
sulfone (PES), polyphenylene sulfide (PPS), polyether nitrile
(PEN), and polyether ether ketone (PEEK). In the present
embodiment, the holder 23 is made of LCP.
[0062] Referring to FIG. 2, the pressure roller 31 as the pressure
rotator includes a cored bar 32 (serving as an axial portion) and
an elastic layer 33 coating the cored bar 32. The pressure roller
31 is driven and rotated clockwise in FIG. 2 by a drive motor.
[0063] The cored bar 32 of the pressure roller 31 is a hollow
structure made of a metallic material. The elastic layer 33 of the
pressure roller 31 is made of material such as foamable silicone
rubber, silicone rubber, or fluoro rubber. A thin release layer
made of PFA, PTFE or the like may be provided on the surface of the
elastic layer 33. The pressure roller 31 is pressed against the
fixing belt 21 to form a desired nip between the fixing belt 21 and
the pressure roller 31. As illustrated in FIG. 3, a gear 45 is
attached to the pressure roller 31 and engages a driving gear of
the drive motor so that the pressure roller 31 is driven and
rotated clockwise in FIG. 2, that is, a direction indicated by
arrow in FIG. 2. Both ends of the pressure roller 31 in the width
direction of the pressure roller 31 are rotatably supported by the
housing 43 of the fixing device 20 through bearings,
respectively.
[0064] A description is provided of a regular fixing process to fix
the toner image T on the sheet P, which is performed by the fixing
device 20 having the construction described above.
[0065] As the body of the image forming apparatus 1 is powered on,
power is supplied to the heater 24 and the motor, and the motor
starts driving and rotating the pressure roller 31 clockwise in
FIG. 2, that is, in the direction indicated by arrow in FIG. 2.
Accordingly, the pressure roller 31 drives and rotates the fixing
belt 21 counterclockwise in FIG. 2 by friction therebetween
generated at the fixing nip N.
[0066] Thereafter, the sheet P is fed from the sheet feeder 12, the
color toner image is transferred onto the sheet P at the position
of the secondary transfer roller 89 and becomes the unfixed color
toner image T borne on the sheet P. As illustrated in FIG. 2, the
sheet P bearing the unfixed color toner image T is conveyed in a
direction indicated by arrow Y10 while the sheet P is guided by a
guide plate and enters the fixing nip formed between the fixing
belt 21 and the pressure roller 31 pressed against the fixing belt
21.
[0067] The toner image T is fixed on a surface of the sheet P under
heat from the fixing belt 21 heated by the planar heater 24 and
pressure exerted from the planar heater 24 (and the holder 23) and
the pressure roller 31 pressed against the planar heater 24
supported by the reinforcement 30. Thereafter, the sheet P is
ejected from the fixing nip and conveyed in a direction Y11.
[0068] A description is provided of a configuration and an
operation of the planar heater 24 (the fixing device 20) in
detail.
[0069] The planar heater 24 in the present embodiment includes a
base 25, the resistor patterns 26 (the resistive heat generators),
conductor patterns 27 (relay portions), power supply electrodes 28
(terminal portions), a base pattern 29 (an identification
information printed portion), and the like.
[0070] At least a surface portion of the base 25 (the surface
portion facing the inner circumferential surface of the fixing belt
21 at the fixing nip) is made of an insulative material. In the
present embodiment, the base 25 is entirely made of the insulative
material (aluminum nitride (AlN) in the present embodiment).
Aluminum nitride is a dark color material and is not suitable for
printing identification information with good visibility.
[0071] The resistor patterns 26 are formed on the surface of the
base 25. Similarly, the conductor pattern 27 is also formed on the
surface of the base 25.
[0072] A current flows through the resistor pattern 26 (that is,
energizing the resistor pattern 26), the resistance of the resistor
pattern 26 generates heat, and the resistor pattern 26 functions as
the resistive heat generator. The resistor pattern 26 is formed by
applying and screen-printing a paste prepared to have a desired
resistance value to the surface of the base 25 and baking the paste
after screen-printing.
[0073] Each of the conductor patterns 27 electrically couples
between the resistor patterns 26 or between the resistor pattern 26
and the power supply electrode 28 to function as the relay portion
that flows the current input from the power supply electrode 28 to
the resistor pattern 26. The conductor pattern 27 is formed by
applying and screen-printing a paste having high conductivity to
the surface of the base 25 and baking the paste after
screen-printing.
[0074] The power supply electrode 28 is electrically coupled to the
conductor pattern 27 and is formed to be able to couple to an
external terminal 56 (see FIG. 7). Accordingly, even when the
surface layer having electrical insulating property and low
friction property is formed on the entire surface of the planar
heater 24, a part of the surface layer over the power supply
electrode 28 is removed to expose the power supply electrode 28 and
supply power to the power supply electrode 28.
[0075] The power supply electrode 28 is made of a silver-based
material such as silver (Ag) or silver palladium (AgPd) in order to
reduce heat generation due to energization. In the present
embodiment, the power supply electrode 28 is formed by
screen-printing the material on the surface of the base 25 and
baking the material after screen-printing.
[0076] The base pattern 29 is made of a material different from a
material of the surface of the base 25. In the present embodiment,
the base pattern 29 is formed of a material other than aluminum
nitride, for example, the silver-based material of the power supply
electrode 28. The base pattern 29 is formed on the surface of the
base 25 to print visible identification information M (see FIGS. 5
and 7). Specifically, in the present embodiment, the base pattern
29 is formed by screen-printing a material having white or a color
close to white on the surface of the base 25 and baking after
screen-printing.
[0077] The identification information M printed on the base pattern
29 is information for specifying (identifying) characteristics and
the like of the manufactured planar heater 24.
[0078] Since screen-printing and other factors vary resistance
values of the resistor patterns 26 of the planar heaters 24
produced, all or a part of resistance values of the planar heaters
24 are measured, and each resistance value or a resistance value in
each manufacturing lot is managed.
[0079] In addition, the planar heaters 24 in the fixing device 20
(the image forming apparatus 1) is used in each destination country
using a working voltage different in each country. Therefore,
different types of planar heaters 24 are used.
[0080] As a result, in order to associate the above-described
information such as the working voltage, the manufacturing lot, and
the resistance value with each of the planar heaters 24 and manage
the planar heaters 24 produced, it is desired to mark the
identification information NI capable of identifying the
above-described information on the planar heater 24 with high
visibility.
[0081] In the present embodiment, the white base pattern 29 is
formed on the base 25 made of a dark color material, and the
identification information M is printed on the white base pattern
29 with dark color ink such as black.
[0082] The above-described configuration improves the visibility of
the identification information M for identifying the manufacturing
lot, resistance characteristics, or the like of the planar heater
24. As a result, the above-described configuration enables a simple
inspection without mistake performed by not only a human but also
an automatic inspection device such as a camera in a manufacturing
process of the planar heater 24 itself, a process of assembling the
planar heater 24 to the fixing device 20, and the like, which
provides stable high quality of the planar heater 24 and the fixing
device 20.
[0083] After the planar heater 24 is manufactured and measured for
the resistance value characteristics or the like, the
identification information M may be printed by an inkjet printer or
the like on the basis of the measured results.
[0084] In particular, with reference to FIG. 3, the identification
information NI of the planar heater 24 is easily visually
recognized even after the planar heater 24 is assembled to the
fixing device 20 (or a subunit modularized with the fixing belt 21
and the like). As a result, the camera or the like can
automatically recognize the identification information NI in an
inspection process of the fixing device 20 (or the subunit) in
which the planar heater 24 is assembled, and the recognized
identification information NI can be stored by a memory disposed in
the fixing device 20 (or the subunit) or set by a dip switch
disposed in the fixing device 20 (or the subunit).
[0085] In the present embodiment, the power supply electrode 28 and
the base pattern 29 in the planar heater 24 are made of the same
silver-based material. The above-described configuration enables
forming the power supply electrode 28 and the base pattern 29 on
the base 25 at the same time and reduces the number of screen masks
necessary for screen printing and the number of steps required for
printing and baking, thereby reducing the manufacturing time and
cost.
[0086] In addition, the power supply electrode 28 and the base
pattern 29 in the planar heater 24 are not electrically connected
to each other. The above-described configuration does not cause a
disadvantage that a current to be supplied to the resistor pattern
26 via the power supply electrode 28 wastefully flows to the base
pattern 29.
[0087] As illustrated in FIG. 5, both the power supply electrodes
28 and the base pattern 29 in the planar heater 24 according to the
present embodiment are disposed on one end portion of the base 25
in the width direction of the planar heater 24 (that is one end
portion of the base 25 in the longitudinal direction of the planar
heater 24, the lower portion of the base 25 illustrated in FIG. 5,
and the left portion of the base 25 of the planar heater 24
illustrated in FIG. 3).
[0088] Referring to FIG. 3, The above-described configuration
associates a work for coupling the external terminals 56 (see FIG.
7) from the outside to the power supply electrodes 28 with a work
for visually recognizing the identification information M printed
on the base pattern 29 in the planar heater 24 attached to the
fixing device 20. That is, since the power supply electrodes 28 and
the base pattern 29 are formed on the same portion of the base 25,
a worker can perform the work for coupling the external terminals
56 (see FIG. 7) to the power supply electrodes 28 while checking
the identification information M.
[0089] As described above with reference to FIG. 3 and the like,
the housing 43 disposed in the fixing device 20 according to the
present embodiment holds both end portions of the holder 23 in the
width direction of the holder 23 holding the planar heater 24 and
both ends of the fixing belt 21 in the width direction of the
fixing belt 21 via the pair of flanges 42.
[0090] The planar heater 24 in the present embodiment is set such
that the base pattern 29 and the power supply electrodes 28 are
outside the housing 43 in the width direction of the housing 43 as
illustrated in FIG. 3. The above-described "the base pattern 29 and
the power supply electrodes 28 are outside the housing 43 in the
width direction of the housing 43" means that the base pattern 29
and the power supply electrodes 28 are at visible positions after
the housing 43 is assembled to form the fixing device 20.
[0091] According to the above-described configuration, the worker
easily and visually recognize the identification information M
printed on the base pattern 29 from the outside and easily couples
the external terminals 56 (see FIG. 7) to the power supply
electrodes 28 from the outside.
[0092] In addition, as illustrated in FIG. 3, the base pattern 29
and the power supply electrodes 28 in the present embodiment are
disposed on a non-driving side of the fixing device 20 (that is the
side on which the gear 45 is not disposed). The above-described
configuration prevents a disadvantage that a member disposed on a
driving side of the fixing device 20 prevents the worker from
visually recognizing the identification information M and a
disadvantage that the gear winds in a harnesses 57 (see FIG. 7) for
power supply.
[0093] As illustrated in FIG. 7, the planar heater 24 according to
the present embodiment includes a cover 55 covering the power
supply electrodes 28 and the base pattern 29 on which the
identification information M is printed.
[0094] As described above, the base pattern 29 and the power supply
electrode 28 are formed of a silver-based material that is easily
corroded. In order to prevent a decrease in visibility of the
identification information M due to corrosion and a power supply
failure due to corrosion, the cover 55 made of a heat resistant
resin such as PPS or PAI covers the base pattern 29 (the
identification information M) and the power supply electrodes
28.
[0095] The planar heater 24 is held by the holder 23 made of LCP or
the like and assembled as a unit in the fixing device 20, and the
external terminals 56 are coupled to the power supply electrodes
28. The power supply is installed in the image forming apparatus 1
and supplies the electric power to the power supply electrodes 28
(that is, the planar heater 24) via the harnesses 57 (that are AC
harnesses) and external terminals 56.
[0096] The planar heater 24 according to the present embodiment is
manufactured by a manufacturing method including the following
process.
[0097] (1) A process forming the resistor pattern 26 and a
conductor pattern 27 electrically connected to the resistor pattern
26 on the surface of the base 25 at least the surface portion of
which is made of an insulative material (see FIG. 6A).
[0098] (2) A process forming the power supply electrodes 28 and the
base pattern 29 on the surface of the base 25 (see FIG. 6B). The
power supply electrodes 28 are electrically coupled to the
conductor pattern 27. The base pattern 29 is made of the material
different from the material of the surface portion of the base 25,
and the visible identification information M is printed on the base
pattern 29.
[0099] The above-described processes may be performed in an order
different from the one described above.
[0100] After these processes are performed, a process forming an
insulation layer, a low friction layer, or the like on the surface
of the planar heater 24 other than the surface of the power supply
electrodes 28 may be performed. In order to expose the power supply
electrodes 28, the power supply electrodes 28 may be masked during
the above process.
[0101] Next, a variation of the present embodiment is
described.
[0102] As illustrated in FIGS. 8A and 8B, the planar heater 24
according to the variation includes the base 25 including a main
base 25a and an insulation layer 25b. The main base 25a is made of
a conductive material such as stainless steel. The insulation layer
is made of glass or the like and formed on the main base 25a.
[0103] Even if the identification information NI is directly
printed on the surfaces of the insulation layer 25b made of
transparent glass with dark color ink, the visibility of the
identification information M is not good because the baked
stainless steel of the main base 25a has a dark color.
[0104] Similar to the above-described embodiment, the planar heater
24 includes the white-based base pattern 29 formed on the base 25
(that is, the insulation layer 25b), and the identification
information M is printed on the white-based base pattern 29 with
dark color ink such as black ink.
[0105] The above-described configuration improves the visibility of
the identification information M for identifying the manufacturing
lot, resistance characteristics, or the like of the planar heater
24.
[0106] Instead of the dark color ink, the identification
information M may be printed on the base pattern 29 with ink having
a color different from the color of the base pattern 29. In order
to visually recognize the identification information M, the base
pattern 29 may be screen-printed except for the position of the
identification information M.
[0107] As described above, the planar heater 24 according to the
present embodiment includes the base 25 having at least the surface
portion made of the insulative material, the resistor pattern 26
formed on the surface of the base 25, the conductor pattern 27
formed on the surface of the base 25 and electrically coupled to
the resistor pattern 26, and the power supply electrode 28
electrically coupled to the conductor pattern 27. In addition, the
planar heater 24 includes the base pattern 29 formed on the surface
of the base 25 and made of the material different from the material
of the surface portion of the base 25 for printing the visible
identification information M.
[0108] As a result, the identification information M on the planar
heater 24 is easily visually recognized.
[0109] In order to improve maintainability of the planar heater 24
and the fixing belt 21 in the fixing device 20 according to the
present embodiment, a subunit may be configured. The subunit may
include the planar heater 24, the fixing belt 21, the flanges 42,
the compression springs 52, a part of the housing 43, and the like
and may be configured to be attachable to and detachable from the
fixing device 20.
[0110] Although the planar heater 24 in the present embodiment
includes the base pattern 29 and the power supply electrodes 28
that are disposed on one end portion of the base 25 in the width
direction of the base 25, the planar heater 24 may include the base
pattern 29 on one end portion of the base 25 in the width direction
and the power supply electrodes 28 on the other end portion of the
base 25 in the width direction. In such a case, insulation between
the base pattern 29 and the power supply electrodes 28 can be
easily ensured.
[0111] Although the planar heater 24 according to the present
embodiment is installed in the fixing device 20, the device in
which the planar heater 24 is installed is not limited to this.
[0112] In such a configuration, similar effects to those of the
above-described embodiment and variation are also attained.
[0113] The above-described embodiments are illustrative and do not
limit this disclosure. Thus, numerous additional modifications and
variations are possible in light of the above teachings. For
example, elements at least one of features of different
illustrative and exemplary embodiments herein may be combined with
each other at least one of substituted for each other within the
scope of this disclosure and appended claims. The number, position,
and shape of the components described above are not limited to
those embodiments described above. Desirable number, position, and
shape can be determined to perform the present disclosure.
[0114] In the present disclosure, the width direction defines a
direction being perpendicular to a direction of conveying the sheet
P and parallel to the axial direction of the fixing belt 21 and the
pressure roller 31.
* * * * *